Question

I’ve the following query:

select wall.postid from wall,posts where  
wall.postid = posts.postid and posts.userid=puserid
order by wall.postid desc LIMIT 4 OFFSET 0;

It returns results in the following manner.

  wall.postid
-----------------
      52
      51
      50
      49

Now I want to save the max value i.e 52 and min value i.e 49 in a variable so that I can use it in my next query.I am using the following query to do so.

select @upper:=max(wall.postid),@lower:=min(wall.postid) from wall,posts where  
wall.postid = posts.postid and posts.userid=puserid
order by wall.postid desc LIMIT 4 OFFSET 0;

I’ve but these variables save the max and min ids of the column not this result set.i.e
it returns me max = 52 and min = 41 which is the minimum value of the column.I need min = 49.

Answer 1

select @upper:=max(`postid`), @lower:=MIN(`postid`) 
from
(
select wall.postid from wall,posts where  
wall.postid = posts.postid and posts.userid=puserid
order by wall.postid desc LIMIT 4 OFFSET 0)m